Li Na struck back for the older generation of women's tennis by fending off gutsy 16-year-old qualifier Belinda Bencic 6-0 7-6 (5) to reach the third round of the Australian Open.

Swiss Bencic, who knocked out Japan's Kimiko Date-Krumm, the oldest woman in the draw in the first round, lost seven straight games before steadying to surprise the Chinese fourth seed with her tenacity in a tense second set played out in stifling heat at Rod Laver Arena.

Bencic, coached by the mother of three-times Australian Open champion Martina Hingis, took what turned out to be the decider deep into the tiebreak but Li sealed the match by crunching a backhand winner down the line.

Pironkova took a medical time out after disappointingly dropping the first set and offered little resistance as the17th seed bageled her in the second - the Bulgarian won just eight points in total in the second set.

"I kept focused on what I wanted to do, kind of not let her have a foot in the door," Stosur said.

"If you can keep going and playing the way that you are and your opponent's not feeling so great, it's even easier to keep going.

"Whereas if you give them that little bit of a sniff, things can start going better, it can become a tight one."

Ivanovic, whose best showing in Melbourne is a final appearance in 2008, beat German Annika Beck6-1 6-2.

Eugenie Bouchard, who turns 20 next month, saw off Virginie Razzanoof France 6-2 7-6 to reach the third round, clinching victory on her seventh match point to equal her best Grand Slam performance to date.

Seeded for the first time at a Grand Slam, Bouchard admitted that breaking through at this level is far from easy.

"It think it's still really tough," she told reporters. "There are some of us who are kind of breaking through a little bit but we still have a lot of tough moments.

"I think the older, experienced players are still dominating but as time goes on, I think I'll do better.

"I've gained experience in the past year and hopefully I can start doing better right away."